Infrared (IR) thermometers, such as IR ear thermometers, are in wide use today. IR thermometers employ an IR sensor to receive and measure IR radiation emanating from a surface. In the case of the IR ear thermometer, the IR sensor detects IR radiation that emanates from the surface of the tympanic membrane. One of the problems encountered in IR thermometry is that the electrical output of most IR sensors is a function of both the IR radiation received through the optical sensor window of the IR sensor, as well as the temperature of the sensor case or housing, typically a metal can.
Some IR thermometer instruments measure the temperature of the IR sensor housing in order to make a correction to the sensor electrical output signal. However, even with temperature sensing of the IR sensor can, there can be measurement errors related to changing temperature gradients across the instrument, particularly across elements of the IR thermometer in and near the optical path to the IR sensor and in the vicinity of the IR sensor housing (the “IR tip assembly”). Several approaches to thermally isolate sensitive areas of the IR thermometer from ambient heat sources have been used, such as the use of thermally insulating sections or the addition of diversionary thermally conductive paths to channel undesired heat flow away from the IR sensor.
Another problem, particularly in patient contact applications such as with IR ear thermometers, is to prevent patient cross-contamination. Generally, a thin plastic disposable cover such as a speculum is placed over an IR tip assembly to minimize the risk of patient cross-contamination as well as to keep the IR tip assembly as free as possible from bodily materials such as cerumen.
Also, regarding the disposable cover, there is an undesirable path for stray conduction of heat energy from the walls of the auditory canal through the disposable plastic cover to the IR tip assembly. There has been some effort to provide disposable covers having thermally insulating materials, however, use of such materials increase the cost of the disposable cover.
What is needed, therefore, is an IR tip assembly that can use a low cost disposable cover without introducing significant measurement error due to undesired heat conduction through the cover.